1. Field of the Invention
The present invention relates to an air intake system structure for supplying air to an engine unit in a motorcycle such as a scooter type vehicle.
2. Description of the Related Art
The basic structure of a scooter type vehicle of this sort is as follows. A floor tunnel is formed between right and left low-floor footrests formed between a front wheel steering unit and a driver's seat. An engine unit is placed in this floor tunnel and covered with a floor tunnel cover. Also, a leg shield connects to the front edges of the footrests and floor tunnel cover.
In a scooter type vehicle in which the engine unit is mounted in the floor tunnel between the footrests as described above, the engine unit is so mounted that its cylinder axis is substantially horizontal and slightly inclined forward and upward. In the front portion of the vehicle, metering instruments, a head lamp, and the like are arranged. The vehicle front portion including these parts is covered with a cowling. In addition, an air cleaner unit for supplying air to the cylinder is connected to the engine unit.
Unfortunately, if particularly a sufficiently large air cleaner capacity is to be secured in this conventional scooter type vehicle, the size of the cowling or the size of the body of the vehicle is increased because the metering instruments, head lamp, and the like are arranged in the vehicle front portion. Also, especially when the air cleaner is mounted above the engine unit and below the seat, the width of the floor tunnel immediately above the engine unit increases. This not only has influence on the driver's riding posture but also increases the size of the body. Furthermore, since the seat height increases, so-called foot resting stability is affected, and the capacity of the trunk after the seat is reduced. Regardless of the position of the air cleaner unit, components of the air cleaner unit, such as a filter and the like, require maintenance. For this purpose, the cowling, seat, or the like must be removed, and this makes maintenance difficult.